Aquarius Yields NASA's First Global Map of Ocean Salinity

NASA's new Aquarius instrument has produced its first global map of the salinity of the ocean surface, providing an early glimpse of the mission's anticipated discoveries.

Aquarius, which is aboard the Aquarius/SAC-D (Satelite de Aplicaciones Cientificas) observatory, is making NASA's first space observations of ocean surface salinity variations - a key component of Earth's climate. Salinity changes are linked to the cycling of freshwater around the planet and influence ocean circulation.

The new map, which shows a tapestry of salinity patterns, demonstrates Aquarius' ability to detect large-scale salinity distribution features clearly and with sharp contrast. The map is a composite of the data since Aquarius became operational on Aug. 25. The mission was launched June 10 from Vandenberg Air Force Base in California. Aquarius/SAC-D is a collaboration between NASA and Argentina's space agency, Comision Nacional de Actividades Espaciales (CONAE).

To produce the map, Aquarius scientists compared the early data with ocean surface salinity reference data. Although the early data contain some uncertainties, and months of additional calibration and validation work remain, scientists are impressed by the data's quality.

The map shows several well-known ocean salinity features such as higher salinity in the subtropics; higher average salinity in the Atlantic Ocean compared to the Pacific and Indian Oceans; and lower salinity in rainy belts near the equator, in the northernmost Pacific Ocean and elsewhere. These features are related to large-scale patterns of rainfall and evaporation over the ocean, river outflow and ocean circulation. Aquarius will monitor how these features change and study their link to climate and weather variations.

Other important regional features are evident, including a sharp contrast between the arid, high-salinity Arabian Sea west of the Indian subcontinent, and the low-salinity Bay of Bengal to the east, which is dominated by the Ganges River and south Asia monsoon rains. The data also show important smaller details, such as a larger-than-expected extent of low-salinity water associated with outflow from the Amazon River.